pH Adjustment in AHA Formulas: Glycolic Acid vs. Citric Acid
Question
If I want to lower the pH in an [url=https://www.myskinrecipes.com/shop/search?search_query=aha&orderby=position&orderway=desc:2edubmnx]AHA[/url:2edubmnx] gel or toner formula to a low range (2.5-3.5), should I use [url=http://www.myskinrecipes.com/shop/%E0%B8%A3%E0%B8%B1%E0%B8%81%E0%B8%A9%E0%B8%B2%E0%B8%AA%E0%B8%B4%E0%B8%A7/660-aha-glycolic-acid-%E0%B8%9C%E0%B8%87.html:2edubmnx]glycolic acid[/url:2edubmnx] or [url=http://www.myskinrecipes.com/shop/%E0%B8%AA%E0%B9%88%E0%B8%A7%E0%B8%99%E0%B8%9B%E0%B8%A3%E0%B8%B0%E0%B8%81%E0%B8%AD%E0%B8%9A%E0%B9%80%E0%B8%84%E0%B8%A3%E0%B8%B7%E0%B9%88%E0%B8%AD%E0%B8%87%E0%B8%AA%E0%B8%B3%E0%B8%AD%E0%B8%B2%E0%B8%87%E0%B8%84%E0%B9%8C/153-citric-acid-%E0%B8%81%E0%B8%A3%E0%B8%94%E0%B8%8B%E0%B8%B4%E0%B8%95%E0%B8%A3%E0%B8%B4%E0%B8%81-%E0%B8%81%E0%B8%A3%E0%B8%94%E0%B8%A1%E0%B8%B0%E0%B8%99%E0%B8%B2%E0%B8%A7.html:2edubmnx]Citric Acid[/url:2edubmnx]? What are the differences between [url=http://www.myskinrecipes.com/shop/%E0%B8%A3%E0%B8%B1%E0%B8%81%E0%B8%A9%E0%B8%B2%E0%B8%AA%E0%B8%B4%E0%B8%A7/660-aha-glycolic-acid-%E0%B8%9C%E0%B8%87.html:2edubmnx]glycolic acid[/url:2edubmnx] and [url=http://www.myskinrecipes.com/shop/%E0%B8%AA%E0%B9%88%E0%B8%A7%E0%B8%99%E0%B8%9B%E0%B8%A3%E0%B8%B0%E0%B8%81%E0%B8%AD%E0%B8%9A%E0%B9%80%E0%B8%84%E0%B8%A3%E0%B8%B7%E0%B9%88%E0%B8%AD%E0%B8%87%E0%B8%AA%E0%B8%B3%E0%B8%AD%E0%B8%B2%E0%B8%87%E0%B8%84%E0%B9%8C/153-citric-acid-%E0%B8%81%E0%B8%A3%E0%B8%94%E0%B8%8B%E0%B8%B4%E0%B8%95%E0%B8%A3%E0%B8%B4%E0%B8%81-%E0%B8%81%E0%B8%A3%E0%B8%94%E0%B8%A1%E0%B8%B0%E0%B8%99%E0%B8%B2%E0%B8%A7.html:2edubmnx]Citric Acid[/url:2edubmnx] in terms of helping adjust formula pH and general properties?
Answer
Adjusting pH in AHA Formulas: Glycolic Acid vs. Citric Acid
When adjusting the pH of an AHA gel or toner formula to a low range (2.5-3.5), Citric Acid is generally the preferred ingredient for pH adjustment.
Here's why and the key differences:
Citric Acid: This ingredient is commonly used specifically for lowering the pH in cosmetic formulations. It allows you to fine-tune the pH of your formula to the desired range (2.5-3.5) without significantly increasing the concentration of the active exfoliating ingredient (like Glycolic Acid) beyond your intended level.
Glycolic Acid: While Glycolic Acid is an acid and contributes to the overall pH of the formula, its primary role is as an active exfoliating ingredient. Adding more Glycolic Acid solely to lower the pH would increase the AHA concentration, which might not be desired and could potentially lead to increased irritation or exceed recommended usage levels.
Key Differences:
- Primary Function: Glycolic Acid is primarily an active exfoliating ingredient that promotes skin cell turnover. Citric Acid is primarily used as a pH adjuster in cosmetic formulas.
- Effectiveness & pH: The effectiveness of Glycolic Acid as an exfoliant is highly dependent on the formula's pH. Lower pH levels (like 2.5-3.5) ensure that Glycolic Acid is in its active, unneutralized form, maximizing its exfoliating potential. Citric Acid is effective at lowering pH across a range.
- Molecule Size: Glycolic Acid has a smaller molecule size compared to Citric Acid, allowing it to penetrate the skin more effectively for exfoliation. While Citric Acid is also an AHA, it is less commonly used as the primary exfoliant compared to Glycolic Acid due to its larger size.
In summary, use Citric Acid to adjust the pH of your AHA formula down to the 2.5-3.5 range after you have added the desired concentration of Glycolic Acid or other AHAs for exfoliation. This allows you to control the pH for optimal AHA efficacy and safety without altering the active ingredient concentration.
Relevant products include Glycopure™ (Glycolic Acid), Ampho-Glycolic™ (Non-Stinging Glycolic Acid Solution), ActiveRelease™ Glycolic Acid (Timed-Release Glycolic Acid), and Citric Acid (Anhydrous, Natural).
